To check whether you have protein crystals in a droplet, you could use
'Izit' from Hampton Research, but FOR A FRACTION OF THE PRICE use
'gelcode blue' stain from 'Biorad' that is used to stain sds-page gels.
If you don't have this in the lab already, ask a biochemist that does to
donate you a small volume, as you buy this in big bottles. Inject one
microlitre into the drop containing the crystals, and if they are
protein, they will absorb the dye and turn brown. Like 'Izit' stain,
this chemical is aqueous.
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